This setting control the maximum number of drivers accessible by a drive letter.

Open the CONFIG.SYS file found in the root directory of your C: drive using Notepad or another text editor (not Microsoft Word or any word processor).

Add a new line with the text "lastdrive=?" where '?' is the last accessible driver letter (for example lastdrive=Z). Alternatively use "lastdrivehigh=?" command to cause the reserved memory to be taken out of the upper memory area instead.

These changes will take place on the next reboot.

Disclaimer: Modifying the registry can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from modifications to the registry can be solved. Use the information provided at your own risk.